Romar, considered an elite recruiter, will be an associate head coach for the Wildcats. He had been the Huskies' head coach for the past 15 seasons before he was fired in March.
A California native with strong West Coast ties, Romar recruited numerous NBA players to Washington, including potential No. 1 overall pick Markelle Fultz. Michael Porter Jr., the No. 1-ranked prospect this year, was also slated to attend Washington but decided to play at Missouri next season after Romar was fired.
"It's an exciting day for Arizona Basketball to be able to welcome Lorenzo Romar and his family to our basketball family," Miller said in a statement. "Lorenzo's accomplishments in this game speak for themselves, including his successful tenure as the head coach at Washington for the last 15 seasons. However, his dedication to his players, passion for this game and impeccable character is what everybody that knows him loves about him.
"He will no doubt make a significant impact in all aspects of our basketball program as we continue to build and improve in all that we do."
Romar coached 13 NBA draft picks at Washington and will replace Joe Pasternack on Miller's staff. Pasternack left to take the head job at UC Santa Barbara.
"Of all the potential opportunities that were out there for me, joining the Arizona program was the one that was the most appealing," Romar said. "I truly believe Sean Miller is one of the best coaches in America. The opportunity to join him, his staff and the rich tradition of Arizona Basketball is something that I'm extremely excited about."